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WSO2 ESB supports a number of different data formats including Plain Old XML (POX), JSON, and SOAP. Translating to a common data model (SOAP in WSO2 ESB) and back to the original format is done using the underlying implementations of message builders and message formatters. If the receiving messages are not in the format the back-end service requires, users can use the XSLT mediator or create a new message in SOAP format using the PayloadFactory mediator.
Also see Normalizer EIPNormalizer for sample scenarios and explanations.